Method of forming earth building blocks



J. A. DAVIS Nov. 13, 1945.

METHOD OF FORMING EARTH BUILDING BLOCKS Filed Nov. 3, 1941 4Sheets-Sheet 1 II p u\ .3 m WM Y 3 ww mm m. Q we & mimfl Q A WWV'INVENTOR JZMEJ A. DAV/5 ATTORNEY J. 'A. DAVIS Nov. 13,. 1945.

METHOD OF FORMING EARTH BUILDING BLOCKS Filed NOV. 5, 1941 4Sheets-Sheet 2 INVENTOR JZMEs ADM 1.;

ATTORNEY J. A. DAVIS Nov.'13, 194s;

METHOD OF FORMING EARTH BUILDING BLOCKS Filed Nov. 3, 1941 4Sheets-Shee1i\ 3 INVENTCR ATTORNEY Nov. 13, 1945. J. A. DAVIS 2,388,679

METHOD OF FORMING EARTH BUILDING BLOCKS Filed Nov. 3, 1941 4Sheets-Sheet 4 Patented Nov. 13, 1945 METHOD OF FOBfiMIN 6. mm nunlnmoLOCKS James A. Davis, Lawrence, Application November 3, 1941, Serial Ni,417,711

Claims.

This invention relates to method and apparatus for producing a, new kindof material, and has particular reference to the fabrication of suitablebuilding material-from ordinary earth and like materials. Thisapplication continues and ex-, tends the inventions shown in myapplication Serial No. 199,721, now matured into U. 8. Patent No.2,265,771.

It is a purpose of the invention to provide a method for constructingbuilding blocks and building material of all shapes, of highlycompressed earth; the earth being of ordinary types commonly found.

It is further an object of the invention to provide building material inshape suitable for building construction, relatively impervious tomoisture, and highly stable. 1

It is a further object of the invention to provide compressed buildingmaterial, having a high tensile strength.

It has been the practice in making structures to be used for buildingsand like purposes to utilize natural earth as found on the site ofconstruction. Such earth has been made more or less permanent in itsproperties by the use of baking in the sun, as in adobe construction, orby moderate compression as in the rammed-earth construction. Thesemethods have been known for many years, and although crude, have beenutilized with moderate success. Both types of construction leave much tobe desired. Both are susceptible to washing away by rain, particularlythe adobe construction. The heat insulation is not high, and thestrength is only moderate. Neither material, as utilized in final form,has any appreciable tensile strength. Cracks are therefore likely toform due to settling of the building, the inducing of tensile stressesthereby, and the inability of the material to resist such tensilestress. Both types of structure have the great disadvantage that theyrequire much time to construct. The adobe construction requires themoulding and pro-baking in the sun which occupies considerable timesince if sun-baking is resorted to, one must wait for favorable weather.

The rammed-earth construction utilizing earth rammed by hand into formsrequires the use of expensive forms, and the speed of construction islimited by the fact that there 'is room for only a few workers at anyone time. The ramming process is slow and one must wait until it iscompleted before he can shift the forms for use on another part of thebuilding. If one attempts to avoid this slowness by providing a greatnumber of separate forms, the cost of theforms becomes prohibitivelyhigh, their transportation becomes expensive, and one is faced with thenecessity of keeping all forms uniform so that a part of the buildingmade with one form will fit a part made with another. Because ,of theawkwardness and slowness of the rammed-earth type of construction,attempts have been made to find a suitable substitute.

The present invention includes the construction of a block of compressedearth of exceptionally high compressive strength and exceptionally hightensile strength. It includes the provision of a machine which willcompress the earth rapidly into suitable blocks, it then being possibleto lay the blocks with great rapidity and to complete a structure withinonly a fraction of the time required for any equivalent alternative.

In the compressed earth construction as used previously, andparticularly as utilized in rammedearth structures, the compression wasnot sufficient to develop the full strength possible in compressedearth. I have found after a long series of experiments that when earthis subjected to unusually high pressures, such as a thousand pounds persquare inch, it acquires a strength far in excess of that which would beexpected on the basis of blocks made with less pressure. There appearsto be a sudden and unexpected acquisition of strength upon the use ofhigh pressures, and although this phenomenon is not yet thoroughlyunderstood, it has been demonstrated adequately by experiment. Apossible explanation is that the various particles comprising the earthmixture are forced into such intimate contact that molecular attractionexists, and the block becomes to all intents and purposes, a solid blockof stone-like material.

The block resulting from the following of operations as described hereinis one possessing new properties not heretofore known in the art. Theblock is different from that met with in the adobe or rammed-earthconstruction in its exceptional strength and imperviousness, and isdifferent from molded blocks such as concrete blocks or baked blockssuch as bricks in having an unusually high tensile strength. The blockcombines in a remarkable way a low cost of fabrication, simplicity infabrication, and at the same time ideal properties for a buildingmaterial. The high tensile strength in particular makes the blockresistant to cracking due to settling or distortion of a building, andalso makes buildings constructed therewith particularly resistant toearthquake. In the case of earthquakes, it is recognized that a greatdeal of damage is done by a compressional and tensile wave which passesthrough the structures. It is the tensile component of this wave whichoften results in destruction. A building material able to resist tensilestress has admirable properties where such conditions are to be met. As

the structure.

To obtain the unusual results described above, it is found desirable toutilize compressive forces of at least 1,000 pound per square inch informing the block. The pressure may be reduced to as little as 500pounds per square inch, with some sacrifice in the strength and otherproperties of the blocks. However, if the pressure is reduced below 500pounds per square inch, it is noted that the compressed block will takeon the character of ordinary rammed earth and will not possess theunusual properties mentioned above. There is'some pressure in thevicinity of 500 pounds per square inch which is critical. Below thispressure, an ordinary mass of earth is obtained. Above this pressure, ablock having unusual strength and other unusual properties as enumeratedabove, is obtained. Why this critical pressure should exist and whythere should be so sharp a threshold is not thoroughly understood.

This fact has been confirmed many times by experiment. An explanationwill probably lie in the fact that when a pressure abov a certaincritical figure is utilized, the pressure is suflicient to distort theindividual particles so that they adhere to adjoining particles over arelatively large area. Otherwise the particles would touch each otheronly at separated points giving limited areas of contact and anegligible adhesion due to the limited contact. Another possibleexplanation is that the water, which is a necessary part of the block,is squeezed into very thin individual films by the high pressure. Thisthin film has a very high tensile strength. If the pressure is notsufficient to develop these very thin films of water, the strengthobtained will be insufficient. Pressures of 1,500 pounds per square inchhave been used successfully in the production of a very satisfactoryblock.

The production of such a block requires the use of the properproportions of ingredients, such ingredients being common and beingclay, soil, sand, and water. The proper proportions are described below.Another remarkable property is that the addition of very smallproportions of addition agents will increase the strength and stabilityfar in excess of what might be expected. Thus as little as five to tenper cent of Portland cement, practically a negligible quantity, willresult in the. doubling of the strength of the block. This cannot be dueto the Portland cement alone since the block will be stronger in tensionthan one made entirely of Portland cement. The addition of suchmaterials as bitumen, or emulsion of various types of asphalt will alsoresult in amazing increases in strength and amazing increases inproperties of stability. Here also, the phenomena are not thoroughlyunderstood, but the results have been proved by numerous tests to bebeyond dispute. A possible theory is that the addition agents cause theparticles to enter into even more aasasvo intimate contact and toProduce a stone-like structure. The addition of the same material willhave practically no effect if the degree of compression of the block isnot carried to the proper point. The new properties resulting from theuse of addition agents described occur only with the unusually highpressures disclosed herein. Thus, if the addition agents disclosedherein are utilized with pressures substantially below 500 pounds persquare inch, the remarkable increase in strength and the remarkableacquisition of other desirable properties will not be noted.

Structures built 'of blocks as fabricated herein and tested have shownunusual stability and unusual strength and have indicated that suchblocks can be utilized as an effective, inexpensive type ofconstruction, one which can be made with material which exists in mostlocalities, thereby eliminating transportation costs.

Reference is had to the accompanying drawings in which:

Figure 1 is a side elevational view of a portable hydraulic press unitfor making blocks according to the invention.

Figure 2 is a top plan view of the unit disclosed in Figure 1.

Figure 3 is a detailed vertical sectional view disclosing the moldingand compressing elements of the assembly.

Figure 4 is a transverse sectional view taken on line 4-4 of Figure 2.

Figure 5 is a detailed transverse sectional view taken on line l55 ofFigure 2.

Figure 6 is a detailed view illustrating the manner in which the moldbox may be opened to accomplish removal of a molded block therefrom.

Figure 7 is a detailed perspective view disclosing the piping system andcontrols for the press embodying this invention.

Figure 8 shows a typical earth block made according to the method of theinvention.

Figure 9 shows a similar block with the addition of stabilizing or othermaterial.

Figur 10 shows still another type or block with addition agents, suchagents being applied only near one face.

Figure 11 shows a cross-sectional view or an earth block having a hollowcavity.

Figure 12 shows a cross-sectional view of the block shown in Figure 11taken across the lines ii -i2.

Figure 13 shows another form of earth block with inserts and passages.

Figur 14 shows a slab of compressed earth, suitable for use as pavingmaterial.

Figure 15 shows an insert to be utilized in making blocks such as shownin Figure 11.

The apparatus disclosed herein for formation of the blocks is intendedas purely illustrative.

Other apparatus may be used to serve the unique- In the drawings,wherein for the purpose of illustration is shown the preferredembodiment of this invention, the reference character It! designates agenerally rectangularly shaped chassis frame which is mounted by meansof the transversely extending springs II on the front and rear axles I2and I3, respectively. A suitable draft bar I4 is connected to the frontaxleand functions to permit the unit to be transported when attached toa suitable motor vehicle.

Referring particularly to Figures 2 to 5, inclusive, there is disclosedtherein a pair of longitudinally extending, transversely spaced angleirons I5 which run parallel throughout their lengths. The opposite endsof these angle irons I5 are suitably secured to the cross members whichform the ends of the chassis frameIIl.

Suitably mounted on the chassis frame I0, directly above the rear axleI3, is an upstanding, triangularly shaped post I6. Spaced longitudinallyof the chassis frame I and suitably supported on the angle irons I is a.second upstanding triangularly shaped post I'I. These post I5 and II arefixed relative to each other and to the frame of the unit. To reinforceand brace the tends between the same, as best illustrated in Figures, 1to 3; inclusive. These posts necessarily are of very rugged constructionfor they sustain the load developed during each compressing operation.

Referring particularly to Figure 6, there is disclosed a mold box in itsopened condition. This box includes a bottom wall I9 and one rigidlyconnected side wall 20. To the free, longitudinal edge of the bottomwall I9 is hingedly connected a movable side wall 2|. A movable topwall22 is hingedly connected to the upper, longitudinal edge of the fixedside wall 20. Figures 1, 2 and 4 disclose the hingedly mounted wa1ls.2and 22 arranged in their closed position. To sustain these walls in thisposition, the free, longitudinal edge of the top wall 22 is providedwith a lip 22a and a suitable number of transverse notches 23. Themovable side wall 2I has mounted thereon to extend longitudinallythereof a rod 24. Pivctally connected to this rod is a series of tiebolt members 25 which are adapted to be positioned within the notches 23of the cover 22. Journaled in the upper ends of these tie bolts 25 is ashaft 26. A handle 21 is fixed to this shaft and functions to enable anoperator to rotate the latter. A suitable number of eccentrics or cams28 are mounted on and fixed with respect to the shaft 26.v It will beappreciated that when the side wall 2| is arranged with itsfree,longitudinal edge seated in the angle formed by the lip 22a and thebottom surface of the top wall or cover 22 with the tie bolts 25positioned within the notches 23, rotation of the shaft 26 will actuatethe cams or eccentrics 28 to tightly clamp these two wall memberstogether.

Figures 3, 4 and 6 disclose the bottom wall I3 of the mold box as havingextending longitu- 'will be more fully explained hereinafter.

Figure 3 clearly illustrates the positioning of a fixed ram 30 withinthe rear, open end of the mold box. This ram is shaped peripherally totightly but slidably fit within the bore of the closed mold box. It isrigidly secured to the rear post I6 by means of the centrally arrangedcolumn 3| and the radially positioned webs 32. This ram 30, of course,is arranged to line up with the longitudinal axis of the mold box.

Referring particularly to Figures 3 and 5, there is disclosed a cylinder33 which is provided with a rigidly secured longitudinally extendingmounting block 34 that rests upon the horizontal, top flanges of theangle irons I5. This mounting block 34, as is best illustrated in Figure5, is shaped to provide a rib which fits between the opposedlongitudinal edges of the angle irons I5. A rigid bracing bar 35 issuitably secured at one end to the upstanding post II. This rigid bar 35extends longitudinally of and overlies the cylinder 33. Clamping straps36 are suitably bolted, or otherwise anchored to the side flange of theangle irons I5 and extend around the cylinder 33 and the bracing bar 35.Two pairs of these straps 30 are provided. The upper ends of the sameare suitably drawn together to tightly clamp the cylinder 33 in place.

This cylinder 33, preferably, is closed with a rounded end 31, as bestillustrated in Figure 3.

The remaining end of the cylinder, the end presented to the mold box, isclosed by a head 38 which may be screw threaded or otherwise secured tothe wall of the cylinder. This head 38 'is provided with a protrudingportion 39 which slidably receives the rod 40 of the packed piston 4|which is positioned within the bore of the cylinder 33. A suitable,heavy spring 42 surrounds the piston rod 40 and bears at its oppositeends against the piston M and the head 38. It is preferred that asuitable packing unit be associated with the bearing 39 and the pistonrod 40.

'No attempt has been made to illustrate the details of such a packingunit. The principal function of such a unit would be to wipe the piston.

ally shaped to tightly but movably fit within the bore of the mold boxto permit movement of this I ram through the box. The ram is bracedwith' respect to the piston rod 40 by means of the central column 44 andthe radial webs 45.

Swung beneath the angle irons I5 and between the longitudinal beams ofthe chassis frame I0 is a tank 46 which is intended to receive the fluidemployed in the hydraulic. system of this press. A suitable filler spout41 is provided for the tank.

A suitable hydraulic pump 43 is diagrammatically illustrated in Figures1, 2 and 7. This pump-preferably is of the rotary type and should be ofa suitable size to be capable of handling pressure up to 1,000 lb. persq. in. with a discharge delivery of not less than 3 gallons per minuteand preferably 6 gallons per minute at a 500 lb. per sq. in. pressure.As r'nany suitable pumps of this character can be-purchased readily,

rioattempt has been made to illustrate the construction of the same.

.The shaft 49 of this rotary hydraulic pump 48 is suitably coupled to agasoline engine designated in its entirety by the reference character50. This power plant preferably is to consist of a 3 H. P., or better a5 H. P., air cooled, 4 cycle engine. Several suitable engines areobtainable on the open market at this time, and for that reason no at-The outlet for the pump 48. is connected to the line 52. This linecommunicates with the bore of the cylinder 33 through the branch 53 at apoint inwardly of the inner end of the piston stroke. Branching off ofthe line 52 is .a line 54 which extends back to the tank 46. A suitablevalve 55 is located in this line 54 and is provided with a controlhandle 56. This valve merely functions to open and close the branch-line 54. When the valve 55 is open, the fluid dischar ed from the pump48 will be returned to the tank 46:for the branch line 54 willconstitute a path of least resistance for the flow of fluid.

, This, of course, is due to the fact that the piston 4| is backed upbythe heavy spring 42. When the valve 55 is closed, the fluid dischargedby the pump 48 will be fed into the cylinder 33 rearwardly of the piston4|. A pop-off or relief valve 51 is provided in a branch line 58 whichextends from the line 52 back to the tank 46. This relief valve, whichmay be of any suitable construction,

is set to open to any desired, predetermined pressure, which preferablywill be 1,000 lb. This pop-oil valve, therefore, will automaticallyoperate to prevent the development of pressure within the cylinder 33 inexcess of the desired maximum pressure.

A further branch line 59 extends between the tank 46 and a point orlocation relative to the length of the cylinder 33 which represents theposition of the piston 4| after it has traveled its full forward stroke.piston has been moved throughout its full compression stroke, it willmove past the point of communication 00 between the cylinder 33 and thebranch line 59. This branch line, therefore,

will be placed in communication with the cylin--v der 33 and the fiuidwill be released from the cylinder for return to the tank 48. A pressuregauge 6| communicates with the bore of the cylinder rearwardly of thefull stroke of the piston 4| so that the operator of the device maymanipulate the valve 55 in accordance with the desired pressure to bedeveloped in the cylinder 33.

Figure l discloses a throttle control lever 82 for the engine 50. Thisthrottle control lever is connected by a cable, or the like, 63 with theoperating lever 56 for the valve 55. This connection is such that whenthe control lever 56 is in the position illustrated in Figures 1 and 7,the valve 55 is open and the engine 50 is idling. When the valve 55 isclosed, the piston 4| will be moved forwardly under the impulse of thecompressing fluid forced into the cylinder 33 by the hydraulic pump 48.The complete cycle of operation is as follows: When the engine 50 isidling, and the valve 55 is in its open position, the liquid is movedfrom the discharge of the pump through the line 52 and through thebranch line 54 back to the tank 46. When the valve 55 is closed, and theengine is accelerated, the pump 48 forces the fluid into the cylinder 33in back of the piston 4|. The piston 4| will be moved through thecylinder against the load of the spring 42 for the purpose ofcompressing the soil which is positioned within the mold box. The piston4| is caused to travel through the cylin- In other words, after the der33 until it reaches its extreme point of forward travel. When this pointis reached, the branch line 59 is placed in communication with thecylinder, at which time the liquid is bypassed back to the tank. If theoperator fails to manipulate the valve 55 after the desired compressingoperation has been performed, the relief valve 51. will function toprevent the development of an excessive pressure in the cylinder 33.After a compressing operation is performed, the operator should returnthe valve 55 to its opened position. The spring 42 then will return thepiston 4| to its starting point and the fluid trapped in the cylinder inback'of the piston will be forced out of the cylinder through the branch53 into the line 52 where it returns to the tank 46 through the branch54 along with the small amount of liquid which is being pumped by pump48 driven by the idling engine. It will be appreciated that should anyof the fluid leak past the piston 4|, it will be permitted to flow backto the tank 46 through the by-pass line 59.

This hydraulic press unit has been developed primarily for the purposeof forming building blocks from ordinary earth or soil. Blocks producedby one of these units have been very successfully employed in theconstruction of buildings. It has been determined that extremely durableblocks may be formed from ordinary soil, although it is preferred to usesoil in a slightly moistened condition. It is only necessary to have asmall percentage of moisture content. Building blocks produced in thismachine under a pressure of approximately 1,000 pounds per square inchhave been found to possess the strength characteristics of a cementblock. If desired, the blocks may be rendered entirely impervious tomoisture by mixing the soil with an emulsified asphalt tempered withborax water. The percentage of emulsified asphalt and borax water isextremely low with respect to the percentage of soil employed in themixture.

It has been found that strong blocks may be made without the use of anybinder whatever.

In the prior art, it had been considered necessary'to use a binder ofsome sort, and to subject the units or structures to heat 01' to thebinding action of some asphaltic compound. However, if the highpressures here specified are utilized, it is found that a strong blockmay be made of even sand and water, no other binder, either organic orinorganic, being required.

The ingredients which have been tried are ordinary top soil of the blacktype with organic decayed matter contained therein, soils of othertypes, clay, sand, sand and gravel mixtures, cinders, stone dust,powdered limestone, brick dust, powdered marble, and other granularinorganic materials. The one ingredient necessary 'besides thesematerials is found to be moisture.

This may vary between the small amount ordinarily supplied by theatmospheric humidity, to approximately 7 per cent. The figure of '7 percent has been found by experiment to yield the best results with mostgranular material. Ordinary earth as dug in its original state willoften have approximately the correct moisture. If it has an excess, itcan be spread out to dry par:

from the ground in different localities will have widely differentcompositions. Some will be very sandy, some high in clay, others rich indecayed organic matter. However, I have not yet found a soil which wouldnot yield good results when compressed as disclosed herein.

As stated previously, the minimum pressure for obtaining theresultsdescribed is approximately 500 pounds per square inch. Belowthis, a weak formless unit is obtained, this being so weak that theblock will often crumble. if one attempts to remove it from thecompression chamber. Above this figure, there is a rapid acquisition ofstrength. As the pressure is raised above 500 pounds the strengthincreases. The range between 1,000 pounds and 1,200 pounds is found togive the best results with most types of soil. Raising the pressureabove 1,200 pounds generally does not give a proportionate improvementin strength, although very successful blocks have been made withpressures of 1,500 and 2,000 pounds per square inch. The costof formingthe block is partially dependent on the pressure utilized, since thisrepresents the amount of work the engine must do and the consequentgasoline consumption. It is believed that the figure of 1,200 pounds persquare inch gives the most value for the energy utilized.

An example of a typical earth block is shown in'cross section in Figure8. Such a block can be formed of earth having the indicated proportionsof soils and sand and may include stones the size of a walnut or evenlargerwithout any appreciable loss in strength. Such a block isindicated generally as 65.

Although it has been pointed out that no binder or addition agent needbe added beyond the soil and moisture itself, it is found that the useof a relatively small percentage of addition agent will result in a verygreat improvement in stability and strength. Thus,.the addition ofapproximately 10 per cent of Portland cement will double the strength ofthe block. As pointed out previously, there is some new and unexplainedaction here, since the resulting block is stronger than one made ofPortland cement formed in the usual way. From-the point of view ofstrength obtained for the Portland cement expended, the figure is fargreater for the earth block with cement added than for othercombinations of Portland cement made in other ways. The proportion ofPortland cement may vary between per cent and 20 per cent, andexperiment with test blocks will often indicate the best percentage. Tenper cent has been found to be the amount which normally gives the mostvalue for the Portland cement added.

Asphalt emulsion can also. be utilized, being added in percentages ofbetween 6 per cent and 12 per cent. The range between 8 per cent and 10per cent is believed to give the most value for the asphalt emulsionadded. Ordinary salt may be mixed with the earth or soil beforecompression, or may be dissolved in the water used to moisten the earth.The use of any of thethree ingredients mentioned immediately above mentwill also have the same effect.

this reason, earth having high contents of soluble salts will be foundto be satisfactory.

When a block has attained equilibrium in the manner described, it willordinarily be impervious to moisture which splashes against it, as mayhappen in rain. This condition is obviously desirable.

In cases in which blocks are made without Portland cement, and evenwhere the block is made with Portland cement or moisture absorbingmaterials, spraying with water shortly after formation appears to causean improvement and to increase strength and stability. The block appearsto gain in strength bystanding, this improvement occurring rapidly for aperiod of about thirty days. After this, it appears to gain strengthslowly so that over a period of approximately five years it should gainin strength appreciably as against its condition when first made.

It has been found that the addition of a small percentage of asphaltemulsion, as taught herein, has the effect of strengthening the blockand giving it better resistance to moisture. The addition of a smallpercentage of Portland ce- Such a block, indicated generally as 66, isshown in Figure 9 with the addition agent interspersed throughout theentire mass of material. Such addition agents may be incorporated in theoriginal mixing of the material for the block. In many cases, the use ofthe addition agent is necessary only on an outer face of the block,although such agent may be applied on two faces or indeed on all thefaces with the central portion omitted. This results in a saving of costof the addition agent, such cost being high relative to the cost of theearth itself, which is usually very low. Such a block is indicatedgenerally as 61 and is shown in Figure 10. The portion having theaddition agent is represented as 68.

results in a stable block; one which maintains condition of equilibriumwithin the block. Some of the soluble materials occurring in ordinarysoil and ordinary earth act in the same way. For

While this portion. has been shown on one face only, it is obvious'thatthe addition agent might be used on the material forming all of thefaces or any desired combination. Further still, an addition agent maybe used for the material in the central part of the block whereconditions make this construction desirable. The manner of forming ablock such as 61 would be to put some earth with addition agent admixedon the bottom of the compressed block with the addition agentincorporated on one side thereof.

Alternatively, the outer portion may have one addition agent and theinner portion still another addition agent. A possible addition agentwould be material to discourage the attack of insects or rodents on thebuilding. Thus, by adding ground glass to the block, rats and similarrodents can be discouraged from gnawing on it. It is found that cattlelike the taste of the compressed earth and are likely to lick the block.This can be discouraged by the addition of creosote. The creosote, inaddition, will act as an insect repellent, and will also serve toprotect any wood which may be placed in contact with the block.

Another addition agent is sodium silicate, which would tend to make theblock more stable and to repel moisture. Another addition agent would bea material which would be deliquescent. Calcium chloride is an example.It has been found that the maximum strength is developed in the blocksif they are kept moist for a period of as much as thirty days afterbeing formed. This moistening is often done by spraying with an ordinarygarden hose. However, by the addition of a material such as calciumchloride, which material will absorb water, the wetting may be doneautomatically, the moisture from the air being attracted and held in thepores of the material.

Molasses or sugar are considered as desirable addition agents to improvethe strength of the blocks. These may be mixed directly in the earthmixture or dissolved in water used to moisten the earth or the finishedblock.

Because of the very great strength of highly compressed earth, it is notnecessary that the blocks be solid throughout. Thus in Figure 11 andFigure 12, are shown two views of a block having a cavity in the center.Such a block is shown generally as 69, with the central portionindicated as 10.. This cavity may be formed or filled with a large stoneor may beformed with a material which'will dissolve or melt out of theblock. Thus a formed block of ice might be placed in the center of themass of earth in the compressing chamber, compression accomplished, andthe finished block removed with the ice in the center.

The ice block may be formed in molds and frozen by the techniques usualin this art. Figure 15 shows such a block H with a projecting ridge 18,which is designed to give more strength I to the block without adding tothe weight thereof.

A small hole may be punched in the block from the outside after forming,thus providing a drain from which the melted ice can escape. Furtheradvantage of this method is that the melted ice will keep the blockmoist for some time and automatically effect the curing which has beenindicated as being so desirable.

In many cases it is desired to fasten pieces to the blocks after theyare laid in place. Although such fastenings as lag screws or expansionbolts can be so placed, it is more convenient to have an insert moldedinto the block. Figure 13 shows a block H with an insert marked 13,which insert is made of metal and is provided with a threaded hole 14.The insert may be held in the compressing chamber and the earthcompressed about it. If it has a dovetailed form asshown, it will beheld firmly in the block after compressing. In other cases, as alsoshown in Figure 13, it is desired to provide passages or grooves in theblocks. Grooves such as 15 may be formed for running pipe, conduit,electric power, or signaling wires. This is formed by providing alongitudinal piece of corresponding shape in the compression box. Such apiece may either be held loosely, to be placed each time the block is tobe compressed, or may be formed in the walls of the chamber itself, anotch of corresponding shape being cut in the end compressing members soas to clear such a longitudinal piece.

A similar technique may be used to form longitudinal holes or passagesI2 in the block to allow the running of electric wires or pipes. Suchpassages can be formed by having a rod placed within the interior of thechamber and having the end members drilled to allow the rod to clearwhen compression is accomplished.

Although water has been mentioned as the agent to wet the earth beforecompression, other liquids may be utilized. Thus, mineral and vegetableoils, organic liquids such as alcohol, gasoline, and other products ofpetroleum distillation may also be employed. Obviously, the cost will behigher for such substances than for water. However, special conditionsmight make the use of these other wetting agents advisable. In the caseof alcohol, the reduced surface tension is helpful to enable the liquidto wet very small particles which are difllcult to wet with water.

In the case of the facings, the outer partof the block may be made of amaterial having an addition agent to obtain decorative effects. Many ofthe ordinar earths have an agreeable color, some being red, others tan,still others black. To obtain a desirable decorative effect, a layer ofearth of the proper color may be put at the bottom of the compressionbox, any other earth placed thereover, and the combination compressed.Alternatively, the bottom layer may be of earth artificially coloredwith mineral coloring matter of non-fading variety. Further still, theexternal surface might be made very smooth by using a polished metalface in the appropriate position in the compressing chamber andutilizing a material such as finely ground marble in the bottom layerand ordinary earth in the remainder. It is possible to produce designsand streaks to simulate real marble by dusting fine granular material ofone color in a definite pattern on the bottom of the compression box,dusting granular material of another color in a uniform layer thereover,putting earth on top of the combination carefully so as to avoiddisturbing the material underneath and afterwards conductingcompression. Obviously, the design should be elongated in the directionof the compression stroke since its features will become compressed whenthe compression operation is conducted.

Because of the high strength and relative imperviousness of highlycompressed earth as taught herein, other forms such as tubes and troughsmay be formed by the techniques described.

Because of the high strength of highly'compressed earth, it is suitableas a paving material. Figure 16 shows a relatively thin slab 16 formedof highly compressed earth as described herein. This will be superior tomany of the other materials utilized for paving in that its tensilestrength will be high and will therefore resist cracking. Anotheradvantage is that its thermal-coeflicient of expansion is very close tothat of the underlying earth, resulting in a minimum of strain being setup by temperature differences. In the making of these paving blocks, itis understood that addition agents will preferably be used to make theblocks stronger and more moisture repellent. Such addition agents canbest be added to the surface which will lie uppermost when the block iscompressed. In other cases, as for instance when the block is to be usedas paving material near the edge or on the shoulders of the road or tobe used in a drainage ditch, the material can best be left as highlypervious as possible so as to permit the drainage of water. It isunderstood that to form such a. relatively thin block, the dimensions ofthe compression chamber, such as shown in Figure 3 will be al-.

The blocks are best cured after being formed by being kept out of sunand wind and sprayed to keep damp for approximately seven days. Thecuring may be omitted and the blocks laid immediately, spraying beingperformed, or if desired omitted, after laying. Particularly whenasphalt emulsion is used with the blocks, the curing period may beomitted.

The blocks may be laid in the usual manner employed for laying eitherconcrete blocks or brick. The standard mortar is applied with a troweland the blocks laid thereupon. A more speedy and economical method maybe utilized, however, in view of the unique properties of the blocks,Since the blocks are very dense and will absorb relatively littlemoisture, the mortar may be made very thin, of the consistency of pasteand may be applied with a white-wash brush instead of a trowel, orbetter, may be applied from a tank and spray unit which will spraya'stream of the thinned mortar on the blocks. Another feature of theblocks which makes this procedure possible is the fact that they arerelatively smooth and ver close to dimension. In using other types ofbuilding units it is necessary to use a thick mortar so as to make upfor the inequalities of the building material. The earth blocks beingvery uniform require little adjustment in the mortar to enable them tolay properly. The use of thinned mortar will result in a much thinnerjoint, This will make for greater strength on the building itself andwill reduce the cost and time of laying the blocks and will furtherreduce the amount of mortar required. Obviously, thinner mortar iseasier to mix, and easier to transport and use.

B the use of less mortar, the cost of the building can be much reducedsince the cost of mortar is high relative to the cost of the blocks. In

general, more desirable results are obtained when the percentage ofmortar relative to the weight of the entire building is kept low.

After the blocks are cured and laid, they may be coated with thin tar orwith the standard cement waterproofing paint. The blocks may also becovered by stucco in the conventional way. In cases where extremevibration or extreme tensile stress are expected, wire mesh may beincorporated in the block. This may be laid in the compressing chamberin layers, the pieces being cut short enough so that their length willapproximately equal that of the compressed block. Alternatively, themesh may be crumpled or folded, and placed in the block to give addedstrength. i

The earth and addition agent, or the earth alone are best thoroughlymixed by standard equipment such as a standard mortar mixer. What isknown as a clod breaker or pug mill may also be used to advantage.Thorough mixture improves the finished .block. The correct percentage ofmoisture will often vary depending upon th'e exact composition of theearth. It is often considered desirable to press test blocks of theearth with varying proportions of moisture, afterwards subjecting theblocks to mechanical tests to determine the best proportion.

It has been determined that the earth or soil within the mold boxcompresses to approximately two-thirds or better one-half its originalvolume. The ram 43, therefore, should be caused to move approximatelyone-third or better onehalf the length of the mold box during movementof the piston 4| from its starting position to the position where theby-pass line 59 is opened or placed in communication with the cylinder33.

It will be appreciated that the compressing of the soil within the moldbox is accomplished by the movement of one ram. To cause all of the soilwithin the mold box to be subjected to a' uniform pressure, the said boxis permitted to float or move forwardly with the ram 43 and relative tothe fixed or stationary ram 30. To effect return of the mold box to itsnormal or starting position, springs 64 are connected to the box and tothe chassis frame l0. These springs are best illustrated in Figures 1and 2.

After a block has been properly formed within the box by the forwardmovement of the ram 43 and the movement of the mold box relative to thefixed ram 30, the mold box may be opened and the formed blocks removedtherefrom. It will be appreciated that suitable cores may be providedfor forming hollow blocks of any desire character.

A very important feature of compressed earth blocks, as disclosedherein, is their ability to resist fire. Tests conducted on individualblocks and on walls made therefrom show that fire has little if anydestructive effect on the blocks; Further still, high temperaturesfollowed by chilling with waterwill leave the blocks unaffected. The useof walls made of earth blocks as fire stops to prevent the spread offire will be found especially effective. For indoor installation whereexposure to weather is not of importance, blocks made of earth withoutany addition agent whatever, but merely compressed, will be found tolast indefinitely and to serve to prevent spread of fire.

The metal used in constructing the various parts of the machine willusually be steel or iron, in the interests of obtaining an inexpensiveunit.

it might have to be transported by mules or by plane, it is desirable toconstruct the various parts of light alloy such as duralumin. It is tobe noted that the assemblage has been so constructed that it is easilydemountable for this typ of, transportation. Thus, by removing thelongitudinal tierod and unbolting, the compression chamber may beremoved separately, as may theend pieces. The engine can be removedseparately, and the hydraulic cylinder 33 may be unbolted by looseningthe clamps 36 and removing as an entire unit. If one removes the wheelsand axles, only the outside frame l0 and the longitudinal angle pieces[5 remain, together with the transverse springs II, the latter-of whichmay be removed if desired. Whether or not the springs are removed, theframe remains as a light and relatively fiat unit which may be easilytransported.

ture has been shown for use in localities where the parts are to behauled over roads. However, where transportation is to be by pack animalor by plane, rails Ill may be extended about a foot on either end of thestructure, thus constituting carrying handles for the entire apparatus.If desired, the gasoline engine, pump, and reservoir can be constructedas one portable unit to be coupled by the various connecting tubes tothe hydraulic cylinder and compressing box assembly. This arrangementwill reduce the size and weight of each unit, so that in many cases, itwill be found unnecessary to disassemble the parts any further thanwould be involved in the mere disconnecting of the engine-pump unit fromthe cylinder-compressing box unit.

The demountable features mentioned above are of great importance in viewof the nature of the apparatus. In many regions, transporting build.

.of the total weight of the building, thus making possible a saving oftransportation of the remaining 90-95 per cent of the weight of thebuilding.

The scope of the invention is indicated by the appended claims.

I claim: 1. In a process for forming a high strength and moistureresistant unit for building purposes, the

steps of admixing a stabilizing agent to granular earth material, ofplacing the said earth with the stabilizing material into position in acompressing chamber in such relation that the earth with the stabilizingmaterial will be on at least one of the exterior faces of the unit aftercompression thereof, of adding other granular earth material free of thesaid stabilizing agent the moisture content of the earth material beingadjusted so as to be substantially seven percent by weight, ofsubsequently applying a pressure in excess of 500 pounds per square inchto the combination of earths, the said pressure being applied from atleast two directions so as to obtain uniform com pression of the earthmaterial, of subsequently removing the pressure, the aforesaidcombination of steps furnishing a building unit having at least aportion thereof stabilized and resistant to mois-' ture and aging, thepressures further serving to give a unit of high tensile strength.

2. In a method of forming a building unit, the steps of moisteninggranular earth material with an insecticide, the quantity added beingsuch as to leave the moisture content substantially within 7 per cent byweight, of compressing the earth and insecticide with a pressure inexcess of 500 pounds per square inch, to form a shaped building block,thereby obtaining a building unit having incorporated in it a materialwhich will prevent attacks by, and be toxic to insects.

3. In a method of forming a building block of relatively'rigidcharacteristics, the steps of adjusting the moisture within earthmaterial to approximately 7 per cent by weight, of subjecting the earthmixture to a uniform pressure in excess of 500 pounds per square inch,thereby forming a shaped building unit, and of curing the shaped unit byrepeated wetting with water for a period of substantially 30 days afterthe formation of the said unit.

- 4. In a method of forming building blocks of high strengthcharacteristics, with a decorative facing thereon, by compressing withina compressing chamber, the steps ofapplying decorative material insubstantially dry form to the interior of the compression chamber insuch relation thatsaid decorative material will be on an exteriorsurface of the block after compression has taken place, of addingearthmaterial so as to lie adjacent to and be bound to the saiddecorative material the moisture content of the said earth materialbeing adjusted so as to be substantially seven percent by weight, ofapplying a pressure to the compression chamber in excess of 500 poundsper square inch, thereby forcing the earth material and the decorativematerial into intimate contact, thereby forming a high strength assaevobuilding unit with thereon.

5. In a method of forming, a building unit of high strength, andstability, the. steps of combining granular earth material, between 1percent and 15 percent of asphalt, of adjusting the moisture content toapproximately 7 percent of the a permanent decorative facing weight ofthe earth material, of applying a pressure of at least 500 pounds persquare inch, on a plurality of surfaces thereof, and of removing thesaid pressure.

6. In a method of forming an earth block to include a material repellentto harmful living organisms, the steps of thoroughly admixing thematerial repellent to living organisms with earth material, of adjustingthe moisture content of the said mixture so as to be substantially 7percent of the weight of the earth material, of exerting a pressure ona, plurality of surfaces of the block in excess'of 500 pounds per squareinch, and of removing the said pressure.

7. In a method of forming a high strength stable earth block with adecorative facing thereon, the steps of placing dry decorative facingmaterial in a thin layer on the bottom of a compression chamber, ofsuperposing on the aforesaid layer earth material, of adjusting themoisture content of the said earth material so as to be substantially 7percent by weight of the earth material, of exerting a pressure inexcess of 500 pounds per square inch on a plurality of surfaces of theblock, and of removing the said pressure,

whereby a strong block with a decorative facing firmly bound thereinwill be formed.

8. In a method of forming a building block of high strength and highstability characteristics, the steps of adjusting the moisture of earthmaterial to substantially seven percent of the weight of the earthmaterial, of compressing the said earth material on a plurality ofsurfaces thereof with a pressure in excess of 500 pounds per squareinch, and of removing the pressure.

9. In a method of forming an earth block with a facing composed ofdecorative material adversely affected by admixture with water, thesteps of applying the said material in dry form, contiguous to a wall ofa compression chamber, of placing earth material close thereto, the saidearth material having its moisture content adjusted so as to besubstantially seven percent by weight of earth material, of subjectingthe combination of decorative material and earth to a pressure in excessof 500 pounds per square inch on a plurality of surfaces thereof, and ofremoving the said pressure.

10. In a method of forming an earth block with a surface composed of a,material to which a stabilizing agent has been added, the steps ofapplying a. relatively thin layer of a mixture of earth and stabilizingmaterial contiguous to a wall of a chamber, of placing moist earthwithout stabilizing material in the said chamber so as to lie close tothe layer of earth with stabilizing material the moisture content of atleast one of the said earths being adjusted so as to be substantiallyseven percent by weight, and subjecting the combination of earth withstabilizing material and earth without stabilizing material to apressure

